This invention relates to a web slitting machine of the type in which a supply roll is unwound, the web is slit and the individual sub-webs are rewound on individual cores in a continuous operation. More particularly the invention relates to apparatus for threading the web and the sub-webs through the machine up to the individual take-up units for each sub-web.
Web cutting or slitting machines are commonly used in the paper industry. In a common design, a supply roll unwind station, guide rollers, and slitters are provided, and downstream of the slitters two stationarily mounted support rollers are arranged at the same height, with transverse spacing from each other. Normally the support rollers include vacuum means. The narrower rolls made from the sub-webs are wound supported by the drums. At the start of the slitting and winding operation, the roll cores, which may consist of cardboard for the narrower rolls, bear on the respective support rollers and at their ends are held by means of suitable clamping means on support arms pivotal against the surface of the support rollers. The end of the sub-web, which is held by the vacuum of the respective support roller, is connected to the reel core, whereupon coiling begins, and the narrower roll is coiled from the respective sub-web on the support roller.
At the start of the working operation, the web must be withdrawn from the wide roll, inserted into the unwinding station and drawn along a guide means formed by a plurality of guide rollers and into the slitter. Following the slitting station in which the wide web is divided into a number of narrower sub-webs, the adjacent sub-webs are alternately conducted to take-up units at the one and the other support roller. The process of drawing the web from the wide supply roll, through the guide rolls and slitter and to the take-up cores, is known as threading.
The take-up units of a support roller have winding axes which are formed by the axes of the roll cores, and which, although they are displaced in the course of the winding by the increasingly larger roll diameter of the narrower rolls, remain substantially in alignment. The take-up units of one support roller form one group, the take-up units of the other support roller form a second group.
The invention is not restricted to the type of winding referred to, i.e. in which two support rollers are present and the winding takes place onto narrower rolls running onto the support rollers. Other take-up units are known which operate with one support roller or no support roller. However, a common property of the designs to which the invention is applicable is that the adjacent sub-webs are conducted alternately to two groups of take-up devices, the winding axes of the groups being spaced apart so that the narrower rolls formed cannot touch each other. By separating the take-up axes of adjacent sub-webs, space is provided for the clamping means engaging the cores of the narrower rolls, and for the corresponding support arms of the clamping means. Thus, in the web slitting machine, these elements extend into the intermediate spaces between axially consecutive narrower rolls of a group of take-up devices.
Threading the web from the wide roll into the unwinding station and slitter, and, in particular, threading the sub-webs amongst the two groups of take-up units, in the past has been carried out by hand. Hand threading represents a time-consuming operation which also involves a certain risk of injury for the operating personnel.
In the company publication of Beloit Lenox Inc., Lenox Mass. (USA) entitled "High Torque Centerwind (HTC) Winder" a web slitting machine is known, which has one support roller against which the roll cores of the narrower rolls are applied from two sides. Threading is by means of a device which includes a rod extending transversely of the web, and which is movable along the path of the web defined by the guide rollers. The web end is connected to the threading rod, for example by adhesives or clips, whereupon the threading rod is set in motion and draws the web along its path through the various stations up to behind the cutting station or slitter. However, bringing the sub-webs formed after the cutting station up to the individual take-up units, which are arranged in two groups having winding axes transversely spaced apart, is then performed by hand, and thus involves delay and a tedious operation for the operating personnel which is not without danger.
A principal object of the present invention is to provide in a web slitting machine an automatic web threading device operating up to the take-up units of each of the individual groups of take-up units.
Another object of the present invention is to provide a web threading apparatus which increases threading efficiency and decreases the amount of time required for threading a web slitting machine, and which can be used regardless of the widths of sub-webs being formed.
Yet another object of the present invention is to provide an apparatus for threading webs through a web slitting machine which reduces the risk of personal injury to operators by eliminating many of the dangerous operations previously performed by hand.